Document EP 0 809 307 A2 discloses a cold band with coating layers of nickel or nickel alloys deposited in a galvanic process. A part of the procedure is, furthermore, an annealing process performed in a multiple sequence, during which the steel band with a nickel coating is first annealed at the temperature of 640° C., i.e., the recrystallization temperature of the steel, with a subsequent annealing process at the same temperature, before another thermal treatment at a furnace temperature of 450° C. finally occurs. A consequence of the sequentially performed annealing processes is a change in the arrangement and nature of the structural crystals. The procedure according to EP 0 809 307 A2 endeavors to accomplish, by selecting corresponding galvanization processes, when the band is deep-drawn or ironed into battery shells that the harder of the two band surfaces later forms the inner side of the battery shell, whereas the other side—also coated with a nickel alloy but of lesser hardness—later forms the outer side of the battery.
Document DE 37 26 518 C2 describes a procedure for producing nickel-plated and cobalt-plated cold band that is subjected to thermal treatment at a temperature in the range of 580° to 710° C. The cold band with a carbon content of up to 0.07 weight % used in this procedure is pickled, cold-rolled, subsequently nickel-plated in a galvanic process, and then annealed at a temperature in the range of 580° to 710° C. to achieve recrystallization. Then follows rerolling or killing of the improved band. The method further proposes to deposit an additional layer of cobalt on the electrolytically applied nickel coating, which has a positive impact on the resistance of the finished band to corrosion. Furthermore, the document points out an enhanced diffusion speed due to the crystallization annealing, where the penetration of the coating metals into the base material of the steel band by way of diffusion demonstrates a depth several times greater than the depth of the nickel-cobalt coating.
Document EP 0 629 009 B1 describes a method for producing of a nickel-plated cold band with very low earing and an especially low carbon content of less than 0.009 weight %. Various alternatives are provided for the performance of the method and the sequence of the individual procedure steps. So, for example, it describes how after the nickel-plating process the annealed steel band is annealed a second time, which, however, results in a costly overall process. Furthermore, the document also describes how the cold band is first annealed and only then subjected to a galvanic process of nickel-plating, without any following diffusion annealing. The temperature range of 600° to 900° C. is indicated for the continual annealing process, and 2 minutes are indicated for the duration of annealing.
The task of this invention is to propose a method for producing improved cold-rolled band that is capable of being deep-drawn or ironed with a carbon content of less than 0.5 weight % resulting in an isotropic steel band that has a low level of texturing and that has a low tendency to form earing.